This proposal seeks to elucidate several mechanisms by which inflammatory cells injure tissue. During acute inflammation neutrophlis accumulate at a tissue target site after diapedesis across vascular endothelium. In vivo the first change after an inflammatory challenge, and prior to diapedesis, is granulocyte margination followed by enhanced vascular permeability. Excessive granulocyte/endothelial interaction may lead to actual vascular damage which may be caused by toxic oxygen species or proteolytic enzymes generated and released by activited neutrophils. I will investigate both the role of reactive oxygen species produced by immune-stimulated neutrophils on mediating tissue (endothelial cell and red cell targets) damage, and will examine how neutrophil lysosomal enzymes can lead to endothelial desquamation and injury. Enucleated neutrophils (cytoplasts)--which are free of granule contents but capable of producing reactive oxygen species upon stimulation--will be exploited to differentiate the relative importance of oxygen radicals and lysosomal enzymes in cellular injury. These cytoplasts can be "rearmed" with lysosomol contents to further evaluate the relative importance of the two. In ancillary studies I propose to pursue my earlier data that activated neutrophils alter endothelial and sub-endothelial adhesogenic proteins, such as fibronectin to make them more adhesive. I shall attempt to more deeply probe interaction of neutrophils with matrix proteins as it may provide an amplification mechanism for inflammation.